Chronic pain is a prevalent, debilitating, and costly national health problem. Nearly half of OEF/OIF Veterans receiving VA health care have at least one documented pain-related diagnosis, yet this high risk population remains understudied. Veterans with chronic pain and co-morbid mental health conditions, especially PTSD, are more likely to receive opioids for pain, to receive higher-dose opioids, and to experience opioid-related adverse events. Thus, it is imperative to better understand how post-deployment PTSD and other mental health problems as well as broad predisposing vulnerability factors such as personality might contribute to the development of chronic pain outcomes and influence health services utilization for pain management. There is also an urgent need to obtain a deeper understanding of OEF/OIF Veterans' perspectives on pain management to develop interventions that promote a patient-centered model of care emphasizing a holistic approach to pain management, including integration of evidence based complementary and alternative medicine (CAM) and other non-pharmacological pain management approaches. The long-term objective of this project is to improve pain management and reduce opioid-related harms for OEF/OIF Veterans with chronic pain and co-morbid mental health conditions. The primary goal of this proposal is to develop a comprehensive model for understanding the development of chronic pain outcomes, utilization of CAM and other non-pharmacological approaches, and utilization of opioid analgesics for chronic pain as well as gain a deeper understanding of Veterans' preferences and attitudes towards pain management approaches. Specific aims are to: 1) Identify predictors of chronic pain among OEF/OIF National Guard Veterans; 2) Characterize patterns of use of CAM, other non-pharmacological pain management approaches, and opioid analgesics; 3) Test a model of health services utilization that identifies prospectively assessed predisposing individual characteristics; facilitators and barriers; and need factors predictive of OEF/OIF Veterans' utilization of CAM, other non-pharmacological approaches, and opioid analgesics; and 4) Identify potential strategies for influencing OEF/OIF Veterans' use of CAM and other non-pharmacological approaches by gaining a richer understanding of patients' experiences with chronic pain and perspectives on pain management health services. The proposed project will capitalize on an existing longitudinal dataset that prospectively assessed 3,458 National Guard Soldiers prior to OEF/OIF deployments (2006-2010) and re-assessed Veterans across post-deployment waves. The current proposal utilizes a multi-phase, mixed methods design guided by an innovative conceptual framework integrating personality theory, a vulnerability-resilience model of chronic pain, and the Andersen Behavioral Model of Health Services Use. It will extend the existing longitudinal cohort by adding an additional wave of quantitative data focused on chronic pain outcomes and in-depth qualitative data examining Veteran perspectives on chronic pain and pain management health services.